Suppose a parabola has vertex (5, –3) and also passes through the point (6, 1). Write the equation of the parabola in vertex form.
A. y = (x – 5)2 – 3
B. y = 4(x – 5)2 – 3
C. y = 4(x + 5)2 – 3
D. y = 4(x – 5)2 + 3

Question

Suppose a parabola has vertex (5, –3) and also passes through the point (6, 1). Write the equation of the parabola in vertex form.  
A. y = (x – 5)2 – 3
B. y = 4(x – 5)2 – 3
C. y = 4(x + 5)2 – 3
D. y = 4(x – 5)2 + 3

parthkohli · Answer

Play smart.

parthkohli · Answer

Eliminate the choices that DON'T have the vertex = (5,-3).

anonymous · Answer

i know its either a or b but from their i dont know what to do.

anonymous · Answer

just kidding i thought it was -5. so it has to be c since thats the only one with +5

parthkohli · Answer

You're perfectly right. Now check if (6,1) is also a point in both the choices.

parthkohli · Answer

No, it's A or B.

anonymous · Answer

a and b both have -5 its +5

parthkohli · Answer

The standard form is this:$$\rm y = a(x - h)^2 + k$$(h,k) is the vertex.

parthkohli · Answer

It's either A or B. Get it now?

anonymous · Answer

yeah i get it now. but how do i check if (6,1) is also a point?

parthkohli · Answer

You plug in 6 for x and 1 for y, then check if both sides are equal.